The map in [4] suggests that every adult in France would have received the BCG vaccine, as they only stopped in 2017 (and receive it as an infant). There are so many confounding variables here, I don't think anyone should be deriving any evidence by looking at the case charts like that.

I agree. I'm not arguing this is 'fact', just an interesting correlation - until proven anything stronger than that - that would explain why some countries got hit worse than others.

As someone else pointed out, the BCG needs a booster. While growing up I was given the initial one and two boosters. Most countries stopped doing that, which could also explain the effect. There's also the matter of which strain was used to create the vaccine: apparently some strains were better at fighting tuberculosis than others, so the same might apply (if the BCG vaccine actually made a difference) to COVID-19.

Anyway, my objective wasn't to start a conspiracy theory. We already have enough of those going around.

Thanks for the 4th link, I couldn't really understand the really sad images and videos coming out of Guayaquil (Ecuador) when comparing them to the rest of South America. Apart from Buenos Aires there are also big metropolises like Sao Paulo or Rio de Janeiro where you couldn't see the same things that were happening in Guayaquil. That vaccination map for South America partly explained the difference for me, at least by correlation.

Yeah, what's happening in Ecuador is incredibly sad. My whole family is in Argentina and I was worried sick for them for a while... who knows, this BCG theory gives me some hope things will be better for them than they are here. Fingers crossed.

"there's an increasing suspicion that countries still using the BCG vaccine for tuberculosis might be seeing [1]way lower infection rates"

Obvious to me, perhaps dumb, question - if countries that were slower to change vaccination regimes have some advantage, then wouldn't we see older people in the countries that did change also at an advantage? Yet all reporting seems to be that older people are harder hit.

BCG vaccine requires a booster every few decades, so it becomes less effective over the years. Apart from health issues related to age, this would explain why old people are at higher risk.